1. Field of the Invention
This invention relates to a switch device having a reversing interlocking mechanism which amplifies a reversing angle of an actuator to operate a switch mechanism.
2. Statement of the Prior Art
Heretofore, a kind of such a switch is disclosed, for example, in Japanese Patent Laid-Open No. 296,312/1987 filed by the present applicant. A reversing interlocking mechanism of the switch device disclosed in the above disclosure will be explained by referring to FIGS. 11 and 12. FIG. 11 is a longitudinal cross section of the main portion of the switch device. FIG. 12 is an explanatory view of operation of the switch shown in FIG. 11.
This switch device includes a switch mechanism which serves to open and close a connection between a movable contact and a stationary contact by reversing action of an actuator 2 in a housing having an upper member 1 and a lower member. The switch mechanism has a movable contact element carried reversibly on a conductive support to be electrically connected to a connecting terminal of an external electric wire and a translator 3 which directly reverses the movable contact element. The reversing action of the actuator 2 causes the connection between the movable contact and the stationary contact to open and close through the reversing action of the translator 3 and the movable contact element.
The translator 3 is formed in three teeth of a gear and is reversibly mounted on the upper member 1 with the tops of the teeth being directed upwardly. The translator 3 engages driving portion 4 which extends downwardly from the actuator 2 mounted reversibly on the upper member 1. The driving portion 4 is formed in two teeth of a gear which are mutually engaged with the translator 3.
However, in the switch device mentioned above, the actuator 2 and the translator 3 are disposed in confronting each other as if external gears mesh as shown in FIG. 12. A center A of rotation of the actuator 2 and a center B of rotation of the translator 3 are positioned away from an acting point C of force, respectively. Thus, the distance between the centers of rotation A and B becomes longer. Consequently, a distance from a support point of the movable contact element of the translator 3 to the top surface of the actuator 2 becomes longer. Accordingly, it is impossible to decrease a total height of the switch device.
In general, in this kind of the switch device, since it is necessary to positively operate an on-off action of the actuator and to operate positively an open and close action between the movable contact and the stationary contact, a reversing angle of the actuator 2 is set to be about 4 to 5 degrees while a reversing angle of the movable contact element is set to be about 9 to 10 degrees. Consequently, as mentioned above, if the height of the switch device becomes larger and the switch device is disposed in a wall of a building so that the surface of the actuator may not come out from the wall prominently, the housing of the switch device will have to project greatly into the wall and the flexibility in disposition of the device with respect to a thickness of the wall will decrease.
Also, in case the actuator 2 covers the whole top surface of the switch device, if the reversing angles of the actuator 2 and the movable contact element are set in a manner mentioned above, the strokes at both ends of the actuator become by far larger than as required.